Smarty does not "change the owner", but Smarty may create directories and if so, these directories inherit the ownership of the running Process (httpd in your case). If you are running safe_mode Smarty must not create any directories so you have to turn use_sub_dirs off and chown templates_c to the same owner as your index.php (or whatever php file the client requests) and make templates_c writable for the httpd-user (via chmod 777 or via group-owenerships and -rights).

I'm pretty sure Smarty's chmodding of the files is not the source of your problems.

additionally: smarty uses http://php.net/tempnam to create files. you should make this work to make wrtiting files work.

and also '/civicrm/files/civicrm/templates_c/en_US/en_US/wrt481b102a63e03'
makes me wonder if the "en_US/en_US/" is the compile_id and the cache_id. if so you don't seem to have use_sub_dirs disabled which is a must to run in safe_mode.

and also:
you still didn't understand safe_mode restrictions. you must not own the templates_c to the user httpd, but to the same owner of the php-file you are requesting. in safe_moce php is only allowed to write into directories that have the same owner as the running script. (in addition to the restrictions the underlying operating system gives to read- and write-permissions)